CN102100047A - Method and system for detecting adjacent channel interference for OFDM/OFDMA based broadband wireless access - Google Patents

Method and system for detecting adjacent channel interference for OFDM/OFDMA based broadband wireless access Download PDF

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CN102100047A
CN102100047A CN2009801277606A CN200980127760A CN102100047A CN 102100047 A CN102100047 A CN 102100047A CN 2009801277606 A CN2009801277606 A CN 2009801277606A CN 200980127760 A CN200980127760 A CN 200980127760A CN 102100047 A CN102100047 A CN 102100047A
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frequency
performance number
aci
carrier waves
gap carrier
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CN102100047B (en
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丁佩律
蔡颖
金小伟
陈香
拉温德拉·P·穆拉特
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Motorola Mobility LLC
Google Technology Holdings LLC
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Motorola Mobility LLC
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/20—Arrangements for detecting or preventing errors in the information received using signal quality detector
    • H04L1/206—Arrangements for detecting or preventing errors in the information received using signal quality detector for modulated signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H04B1/1027—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes
    • H04J11/0023—Interference mitigation or co-ordination
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2602—Signal structure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Quality & Reliability (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Monitoring And Testing Of Transmission In General (AREA)

Abstract

Disclosed are a method and a system for detecting adjacent channel interference between two systems having neighboring frequencies. The method and system calculates (802) a Fast Fourier Transform (FFT) output for one or more upper and lower frequency side null subcarriers and center data subcarriers of a frequency channel. Power values are calculated (804, 806) for the upper and lower frequency side null subcarriers and the center data subcarriers for use in determining a presence of adjacent channel interference (ACI).

Description

Be used to detect method and system based on the adjacent-channel interference of the broadband wireless access of OFDM/OFDMA
Technical field
Present invention relates in general to mobile communication system, and relate in particular to the method and system that is used for detecting based on the adjacent-channel interference (ACI) of the BWA of OFDM (OFDM)/OFDMA.
Background technology
For two communication systems of operating on nearby frequency bands, the adjacent-channel interference in nearby frequency bands (ACI) is caused by the unwanted emission that the imperfection because of emission filter causes usually.Fig. 1 is the figure of the frequency spectrum 100 of expression two conventional Frequency Division Duplexing (FDD) (FDD) system of using nearby frequency bands.The up link (UL) of " FDD A " system is adjacent to the UL of " FDD B " system.Equally, the down link of FDD A system (DL) is adjacent to the DL of " FDD B " system.The duplex separation gap is shown as from the starting position of the frequency of the UL of FDD A system extends to the starting position of the DL of FDD A system.If between the DL of the UL of FDD B system and FDD A system little frequency gap is only arranged, then between near the travelling carriage (MS) identical base station (BS), two positions and two ACI can appear.
Fig. 2 is the block diagram that the frequency spectrum 200 of the FDD system of nearby frequency bands and time division duplex (TDD) system is used in expression.The UL of FDD A system has the frequency adjacent to " TDD B " frequency band.The DL of FDDA system is adjacent to the 2nd TDD B frequency band.When two related systems are two nonsynchronous TDD or a TDD and a FDD, between near the MS the identical BS in two positions and two, can there be ACI.Owing to the mobility that is associated with MS with to the size of mobile phone and the restriction of cost, it is the most problematic ACI type that MS and MS disturb.Specifically, when the size of MS reduces to obtain maximumly when portable, the size of the RF filter that uses in MS is very limited.Under current wave filter technology, challenging is that foundation can realize the RF filter of needed decay with very little frequency shift (FS), alleviates MS and MS interference to use such finite size.On the other hand, the RF filtering performance of raising MS also requires additional manufacturing cost.In the high user density zone such as railway station and cafe, two MS can (several meters) closer to each other, and short distance therebetween may cause serious degradation or guarantee that big frequency protection band is to alleviate ACI.BS and BS disturb and also may require to install additional channel filter (one or more) in BS.
Be the frequency spectrum of boundary belt in order to save as much as possible being wasted, carried out several trials and alleviated ACI.ACI alleviates example using system of method to be coordinated, the information whether system coordination need exist about ACI.In the system coordination example, the channel marginal belt bandpass filter that system is used for code division multiple access (CDMA) system detects the ACI existence.Basically, alleviate method and ACI testing process, and the filter that is used for cdma system need be become matching chip waveform and receiver filtering by specific design for cdma system design ACI.
If use ACI removing method, then need to determine the existence of ACI, because such method causes unnecessary computation burden usually when ACI does not exist based on signal processing.
In another example, if two systems all are TDD, then when a system works up link in the cycle and another when being operated in the downlink period, can reduce service time regularly overlapping synchronously.Yet it is that FDD and another are the situation of TDD and the situation that has two FDD systems of little frequency gap between the UL piece of the DL of the A of system piece and the B of system as shown in fig. 1 that such method is not suitable for a system.And, disturbing in order intactly to eliminate MS and MS, two TDD systems need have identical downlink/uplink and divide and frame duration.
In another example, a kind of existence of coming technology that MS between the minimization system and MS disturb to detect ACI of being used for by signal interference-to-noise ratio (SINR) change and the signal energy of following the tracks of at MS via the coordination between the system.Yet this technology does not adopt the spectrum signature of ACI, and the spectrum signature of ACI has higher energy usually in channel edge.Therefore, detection method does not provide reliable result.
Description of drawings
When read in conjunction with the accompanying drawings,, can understand the present invention itself best by detailed description with reference to following illustrative embodiment, in the accompanying drawings:
Fig. 1 is the block diagram of the frequency arrangement of expression two conventional Frequency Division Duplexing (FDD) (FDD) system of using nearby frequency bands;
Fig. 2 is the block diagram that the frequency response of the conventional FDD system of nearby frequency bands and conventional time division duplex (TDD) system is used in expression;
Fig. 3 is standard World Interoperability for Microwave Access, WiMax (WiMax) OFDM (OFDMA) sub-carrier structure;
Fig. 4 is the curve chart of the frequency response of wideband OFDM/OFDMA signal of being included in the unwanted frequency response that transmits in the adjacent channel;
Fig. 6 illustrates the drawing of the sub-carrier positions of two 10MHz WiMAX systems in adjacent channel;
Fig. 7 be expression according to an embodiment of the invention, be configured with and realize that ACI detects the block diagram of the example radio equipment of needed Functional Capability;
Fig. 8 is the block diagram of the transceiver of Fig. 7 according to an embodiment of the invention;
Fig. 9 is a flow chart according to an embodiment of the invention, that be used for detecting in the WiMAX system that adopts OFDMA the processing of ACI;
Figure 10 is the block diagram of the ACI detector of Fig. 8 according to an embodiment of the invention.
Embodiment
Illustrative embodiment provides a kind of method and system, is used for utilizing the gap carrier wave and the performance number that is associated with it detects adjacent-channel interference (ACI) in the OFDM/OFDMA system to detect ACI.
In the following detailed of exemplary embodiment of the present invention, describe with enough details and can implement certain exemplary embodiments of the present invention, so that those skilled in the art can implement the present invention, and be understood that, can utilize other embodiment, and can under the situation that does not depart from the spirit or scope of the present invention, can carry out logic, framework, programming, machinery, electronics and other changes.Therefore, do not treat following detailed with restrictive meaning, and the scope of the present invention that only is defined by the claims.
In the description of accompanying drawing, those similar title and Reference numerals with formerly accompanying drawing (one or more) are provided to similar element.Concrete Reference numeral to the element assignment only is provided to help to describe, and does not mean that hint any limitation of the invention (26S Proteasome Structure and Function).Should be understood that concrete assembly, equipment and/or parameter name only are for example, and do not mean that the hint any limitation of the invention.Therefore, can unrestrictedly use the different vocabulary/terms of the assembly/equipment/parameter that is used to be described in this to realize the present invention.Providing utilization under the contextual situation of each term of this utilization, provide its wideest explanation to this term.
Fig. 3 is standard World Interoperability for Microwave Access, WiMax (WiMax) OFDM (OFDMA) sub-carrier structure 300 that is used for an embodiment described herein.For the OFDM/OFDMA system, be the subcarrier of given number with channel distribution.Usually, subcarrier can be divided into data subcarrier, pilot sub-carrier, DC subcarrier and gap carrier wave (protection subcarrier).Wherein, create the gap carrier wave by the modulation symbol that loads null.Therefore, on the gap carrier wave, there is not signal energy.The gap carrier wave is also referred to as protection and substitutes virtual subnet carrier wave or untapped subcarrier.
The OFDM/OFDMA system can distribute the gap carrier wave of given number at the channel edge, to allow signal spectrum to descend and to satisfy bandwidth requirement.For example, for 10MHz WiMAX system, contrary fast fourier transform (IFFT)/the fast Fourier transform (FFT) size is 1024 subcarriers, and wherein, 184 are used as the gap carrier wave.At receiver side, the FFT of those gap carrier waves output is dropped, and does not further handle, because the gap carrier wave does not comprise information.Yet, according to a preferred embodiment of the present invention, can use FFT to export and derive ACI.
Fig. 4 is the curve chart 400 of the frequency response of wideband OFDM/OFDMA signal.Because the imperfection of emission filtering, signal energy leaks into outside its channel span that is assigned usually.The frequency spectrum of OFDM/OFDMA modulation signal descends with the order of magnitude of 1/f usually, and wherein, f is the frequency at the channel edge.Therefore, as shown in the figure, have high-energy at the channel edge usually by ACI signal in adjacent channel apparatus operating experience, and for the low relatively energy of existence for the frequency at channel edge.
Fig. 5 is illustrated in the drawing 500 of the sub-carrier positions of two 10MHz WiMAX systems that launch in the adjacent channel.Be provided with according to the WiMAX system based on OFDMA, the frequency of employed subcarrier takies less than the channel width that limits, and the frequency of all subcarriers takies greater than channel width.For example, the WiMAX system with 10MHz channel size has subcarrier and 184 gap carrier waves of 840 uses, and sub-carrier frequencies is 10.94KHz at interval.The frequency span that this means whole 1024 subcarriers is 10.94x1024=11.2MHz, and the subcarrier that uses takies the frequency of 9.189MHz.Therefore, as can be seen, as can be, when the WiMAX system with two 10MHz places adjacent channel and during without any the additional external boundary belt, in fact the part of the gap carrier wave of a system is positioned at the channel of another system as shown in Fig. 5.
As the result of the combination of the frequency span of the expansion outside 10MHz and the frequency response of ACI (referring to Fig. 4), when system experiences strong ACI source on high frequency side or lower frequency side, the power of system's experience on outermost gap carrier wave.Therefore, according to embodiments of the invention, the FFT of those gap carrier waves output can be used to detect the existence of ACI.
Fig. 6 be expression according to an embodiment of the invention, be configured with and realize that ACI detects the block diagram of the example radio equipment of needed Functional Capability.According to illustrative embodiment, wireless device 600 is honeycomb/mobile phones.Yet, can understand that function of the present invention is applicable to the radio or the wireless device of other types, and only be provided for explanation as the explanation and the description thereof of cellular wireless device 700.
Wireless device 600 comprises central controller 605, central controller 605 be connected to memory 610 and control wireless device 600 traffic operation, traffic operation comprise radio signal generation, transmit, receive the decode.Controller 605 can comprise programmable microprocessor and/or digital signal processor (DSP), the allomeric function of programmable microprocessor and/or digital signal processor (DSP) control wireless device 600.For example, programmable microprocessor and DSP carry out controlled function that is associated with processing of the present invention and other controls, data processing and the signal processing that is needed by wireless device 600.In one embodiment, the microprocessor in controller 605 is conventional multipurpose microprocessor, and such as MCORE family processor, and DSP is 56600 series DSP, and wherein each can obtain from Motorola Inc..
As shown in the figure, wireless device 600 also comprises input equipment, and its keypad 620, volume controller 625, microphone 627 and additional microphone 629 are shown as and are connected to controller 605.In addition, wireless device 600 comprises the output equipment that also is connected to controller 605, and output equipment comprises internal loudspeaker 630 and selectable display 635.According to illustrative embodiment, wireless device 600 also comprises I/O (I/O) jack 640, and I/O jack 640 is used to insert external loudspeaker (642), and this external loudspeaker (642) is illustrated as the headphone of wired connection.In substituting realization, and as shown in drawings, realize that the headphone 647 of bluetooth is provided as external loudspeaker, and communicate via Bluetooth adapter 645 and wireless device 600.
These input and output devices are coupled to controller 605, and allow the user to dock with wireless device 600.For example, it is the signal of telecommunication that microphone 627 is provided for the speech conversion from the user, and internal loudspeaker 630 provides audio signal (output) to the user.These functions can further be realized by speech coders/decoders (vocoder) circuit (not shown), and the conversion of modulus and/or digital and analogue signals can be provided, and speech coders/decoders (vocoder) circuit is connected to controller 605 with microphone 627 and loud speaker 630.
Except top assembly, wireless device 600 further comprises transceiver 670, and transceiver 670 is connected to antenna 602, receives digitized radio frequency (RF) signal at antenna 602.Make wireless device 600 to send the wireless RF signal and to receive the wireless RF signal with the transceiver 670 of antenna 602 combinations to wireless device 600 from wireless device 600.Transceiver 670 comprises radio frequency modulator/demodulator circuit (not shown), and radio frequency modulator/demodulator circuit transmits and receives the RF signal via antenna 602.When wireless device 600 is mobile phone, in the received RF signal some can be converted to the audio frequency of exporting during ongoing telephone conversation.Audio frequency output initially generates at loud speaker 630 (or headphone 647 of external loudspeaker 642 or realization bluetooth) with default volume level (that is, the user before the dynamic adjustment that is realized by the present invention is provided with), listens to for the user.
When wireless device 600 was mobile phone, wireless device can be the GSM phone, and comprised and wherein, can insert outside SIM card 665 by subscriber identity module (SIM) card adapter 660.SIM card 665 can be used as storage facilities.SIM card adapter 660 is coupled to controller 605 with SIM card 665.
Except top nextport hardware component NextPort, the several functions and the special characteristic of the present invention of wireless device 600 are provided as software code, and this software code is stored in the memory 610, and are carried out by the microprocessor in the controller 605.Microprocessor is carried out various Control Software (not shown), so that the integral body control to wireless device 600 to be provided, comprise that adjacent-channel interference (ACI) detects, and for the present invention more specifically, microprocessor is carried out the software that the adjacent-channel interference that realizes use gap carrier wave detects (ACID).Jointly provide the software of function of the present invention and/or the combination of firmware to be referred to herein as (ACID) utility.
As the invention provides and shown in the memory 610, ACID utility 650 has the ACID database 655 that is associated with it.Be described in more detail below the function of ACID utility 650 and ACID database 655.Yet when being carried out by microprocessor, the key function that is provided by ACID utility 650 includes, but are not limited to: the gap carrier wave of (1) lower frequency side and high frequency side calculates; (2) the centre data subcarrier calculates; (3) at the gap carrier wave of lower frequency side, calculate at the gap carrier wave of high frequency side and the average total power of central data subcarrier; 4) central authorities are calculated with the lower frequency side power ratio; 5) central authorities are calculated with the high frequency side power ratio; And 7) ACI assessment is used for coming the protection system performance and improving user experience by proofreading and correct detected ACI.The result of calculation that 655 storages of ACID database are generated by ACID utility 750.
The one of ordinary skilled in the art will understand, and the hardware of describing in Fig. 6 can change according to realization.Except or replace the hardware of describing among Fig. 6, can use other internal hardwares or external equipment.And processing of the present invention can be applied to the portable/handheld data handling system or the similar devices that can generate audio frequency output.Therefore, described example does not mean that hint is for architectural limitation of the present invention.
Fig. 7 is the receiver 774 of transceiver 670 and the block diagram of transmitter 794.According to one embodiment of present invention, receiver 774 realizes that ACI detects.Receiver 774 and transmitter 794 all are coupled to antenna 602 via switch 720.Receiver 774 has WiMax receiving element 776, is used to receive and handle WiMax signal received, that have frame or grouping.Receiving element 776 is coupled to FFT calculator 778.FFT calculator 778 calculates the FFT output that the ACI that sends in the ACI correcting unit 782 alleviates a plurality of subcarriers of unit 784.Detect the gap carrier wave by the ACI detector 786 in the ACI correcting unit 782.Output from ACI correcting unit 782 is further processed in the back level of receiver 774.Transmitter 794 comprises WiMax transmitter unit 796, is used to handle the WiMax signal that will launch and generates the RF signal that will send to antenna.
Fig. 8 is the flow chart that is used for detecting in the WiMAX system that adopts OFDMA the processing 800 of ACI.To describe in combination with Fig. 9 and handle 800, Fig. 9 is the block diagram of the ACI detector 786 of use in the transceiver 670 of Fig. 7.To handle 800 at having such as describing in conjunction with the example of the 10MHz WiMAX system of the above-mentioned gap carrier assignments of Fig. 5.However, this processing is applicable to other OFDM/OFDMA systems easily, and other OFDM/OFDMA systems unrestrictedly for example are the Long Term Evolutions (LTE) with different channels size.
Handle 800 in frame 802 beginnings, the FFT output (one or more) of wherein calculating the gap carrier wave that is positioned at the channel width outside.In step 803, gap carrier wave (high frequency side) detector 902 of high frequency side frequency band and lower frequency side frequency band and gap carrier wave (lower frequency side) detector 904 detect frequency gap carrier wave from FFT output (one or more) respectively.For example, can be to be in the 10MHz of width of channel and those gap carrier waves between the 11.2MHz at the gap carrier wave outside the channel width.For the setting of Fig. 5, have numbering 0～54 gap carrier wave and be used for lower frequency side, and the subcarrier with numbering 969～1023 is used for high frequency side, it is outside channel width 10MHz.In equation Eq (1), specified i the symbol that is used for the lower frequency side subcarrier.
y l(i)＝[y 0(i)，...y 54(i)] T Eq(1)
Wherein, y l(i)=[y 0(i) ... y 54(i)] TBe the FFT output of the gap carrier wave of predetermined number; And T is a transpose operator.In this embodiment, 0...54 is the index of 55 predetermined sky (lower frequency side) subcarriers of selecting.
In equation Eq (2), specified i the symbol that is used for the high frequency side subcarrier.
y u(i)＝[y 969(i)，...y 1023(i)] T Eq(2)
Wherein, y u(i)=[y 969(i) ... y 1023(i)] TBe the FFT output of the gap carrier wave of predetermined number; And T is a transpose operator.In this embodiment, 969...1023 is the index of 55 predetermined sky (high frequency side) subcarriers of selecting.
At frame 804,, calculate average total power P according to equation Eq (3) by the average total power calculator 914 that is used for lower frequency side (1) in the ending of frame 1
P l = 1 N Σ i = 0 N - 1 y l ( i ) H y l ( i ) - - - Eq ( 3 )
Wherein, l represents lower frequency side; H is the conjugate transpose operator; N is the number of the symbol in the frame that receives; And i represents i symbol.
Calculate average total power P by the average total power calculator 912 that is used for high frequency side (u) according to equation Eq (4) u
P u = 1 N Σ i = 0 N - 1 y u ( i ) H y u ( i ) - - - Eq ( 4 )
Wherein, u represents high frequency side; H is the conjugate transpose operator; N is the number of the symbol in a frame; And i represents i symbol.
At frame 806, the FFT output of central data subcarrier that is positioned at the middle body of channel is calculated by FFT 778, and is detected by central data subcarrier detector 906.The central data subcarrier is assigned as in use.In addition, at frame 806, the average total power calculator 916 that is used for central data subcarrier (c) calculates the average total power P of central data subcarrier (for example, 55 subcarriers) according to equation Eq (5) c
P c = 1 N Σ i = 0 N - 1 y c ( i ) H y c ( i ) - - - Eq ( 5 )
Wherein, y c(i)=[y C1(i) ... y C55(i)] TBe the FFT output of the data subcarrier of 55 uses; C1 ..., c55 is the index of the central data subcarrier of those selections; H is the conjugate transpose operator; C represents the central data subcarrier; And i represents i symbol.In this example, use 55 subcarriers.Yet for different frequency structure, the number of subcarrier can change.
At frame 808, central authorities calculate average power P at central data subcarrier than calculator 924 according to equation Eq (6) with low-power cAverage power P with lower frequency side gap carrier wave lBetween the first ratio (γ l)
γ l = 10 * lg ( P c P l ) - - - Eq ( 6 )
Wherein, lg is a logarithmic function.
At frame 814, central authorities calculate average power P at central data subcarrier than calculator 922 according to equation Eq (7) with high power cAverage power P with high frequency side gap carrier wave uBetween the second ratio (γ u)
γ u = 10 * lg ( P c P u ) - - - Eq ( 7 )
Wherein, lg is a logarithmic function.
At frame 810, in ACI evaluator 930 with the first ratio (γ 1) and threshold (for example, γ l＜threshold value) is used to assess the existence of the ACI on the lower frequency side.If determine the first ratio (γ at frame 810 l) greater than threshold value, then on lower frequency side, there is not ACI (frame 820).Yet, if determine the first ratio (γ at frame 810 l) less than threshold value, ACI is arranged on lower frequency side then.At frame 812, the startup that alleviates the ACI on lower frequency side takes place.
At frame 816, in ACI evaluator 930 with the second ratio (γ u) and threshold (for example, γ u＜threshold value) is used to assess the existence of the ACI on the high frequency side.If determine the second ratio (γ at frame 816 u) greater than threshold value, then on high frequency side, there is not ACI (frame 820).Yet, if determine the second ratio (γ at frame 816 u) less than threshold value, ACI is arranged on high frequency side then.At frame 818, the startup that alleviates the ACI on high frequency side takes place.
ACI evaluator 930 comprises threshold calculations device 932, threshold value adjuster 934 and comparator 936.In frame 810 and 816, come calculated threshold according to equation Eq (8)
β-Δ(dB) Eq(8)
Wherein, the parameter Δ is the compromise adjustable parameter that is used to realize between false alarm rate and the loss.According to equation Eq (9), come the predefine parameter beta by value.
β = 10 * lg ( P c P l ) - - - Eq ( 9 )
Wherein, the value that has of parameter beta is corresponding to the average power P of the central data subcarrier of the communication system that does not have ACI in the adjacent channel that is illustrated in communication system cAverage power P with lower frequency side gap carrier wave lBetween ratio.The unwanted transmit leakage performance of main system that can be by wireless device 600 decides parameter beta.
Threshold calculations device 932 calculating parameter β, and threshold value adjuster 934 calculating parameter Δs and this adjustment is applied to threshold calculations device 932 are with the expression formula β-Δ that draws equation Eq (8).This threshold value is compared the existence that device 1036 is used to assess ACI.
In case determined the existence of ACI, then ACI alleviates unit 784 these results of application to alleviate variation.The example that alleviates comprises the coordination between two systems for the situation about disturbing for MS and MS or the application of the ACI elimination algorithm by signal processing.
Can be readily seen that top processing 800 is the ACI detection methods that are used for the power output of common those gap carrier waves of use based on the OFDM/OFDMA system.Handle 800 and effectively utilize the frequency response characteristic of ACI signal and the gap carrier assignments in the OFDM/OFDMA system.
Handling 800 advantage is, only can realize this processing to the simple additives according to the software of ACID utility 750, and not need additional firmware or system design to revise.Handling 800 can utilize simple adjustment easily to be applied to system such as WiMAX, LTE etc.In addition, can alleviate the method combination with known ACI, with protection system performance effectively and improve the experience of user to ACI with handling 800.
In the superincumbent flow chart, in some implementations, under situation without departing from the spirit and scope of the present invention, can make up, carry out or perhaps omit the particular step of handling simultaneously or with different orders.Therefore, though describe and method step has been described with particular order, the use of particular sequence of steps does not mean that the hint any limitation of the invention.Under the situation that does not depart from the spirit or scope of the present invention, can change for order of steps.Therefore, do not treat the use of concrete order with restrictive meaning, and the scope of the present invention that only is defined by the claims.
Will be further understood that, can use any combination of software, firmware or hardware to realize processing in the embodiments of the invention.As for software implementation preliminary step of the present invention, programming code (no matter being software or firmware) will be stored in one or more machine-readable storage medium usually, all fixing in this way (hard disk) drivers of these one or more machine-readable storage medium, dish, CD, tape, such as the semiconductor memory of ROM, PROM etc., make article according to the invention thus.Use the goods that comprise this programming code by following manner: carry out directly code from storage facilities, to copy to from the code of storage facilities in another storage facilities such as hard disk, RAM etc., or use such as the transmission type media of numeral and analog communication links and launch the code that is used for long-range execution.Make up the code that wherein comprises to carry out by comprising, can implement method of the present invention according to one or more machine readable storage facilitiess of code of the present invention and suitable processing hardware.Being used to implement device of the present invention can be one or more treatment facilities and stocking system, and these one or more treatment facilities and stocking system comprise the program (one or more) of the coding according to the present invention or have the network insertion power of the program (one or more) of coding according to the present invention.
Those skilled in the art will understand, the software aspect of illustrative embodiment of the present invention can be distributed as the program product of various ways, and illustrative embodiment of the present invention is suitable for with being equal to, and irrelevant with the particular type of the medium that is used for actual execution distribution.For example, the tabulation of the nonexcludability of media type comprises: but record type (tangible) medium, such as floppy disk, thumb actuator, hard disk drive, CD ROM, DVD; And transmission type media, such as numeral and analog communication links.
Though reference example embodiment has described the present invention, those skilled in the art will understand, under the situation that does not depart from scope of the present invention, can carry out various changes, and can substitute its element with equivalent.In addition, under the situation that does not depart from its necessary scope, can carry out many modifications so that its particular system, equipment or assembly are adapted to instruction of the present invention.Therefore, be intended to the invention is not restricted to disclosedly be used to carry out specific embodiment of the present invention, but the present invention will comprise all embodiment that drop in the claim scope.And any order or importance are not represented in the use of first, second grade of term, but first, second grade of term is used for an element and another element are distinguished.

Claims (20)

1. in communication system, a kind of method comprises:
The fast Fourier transform (FFT) output of the one or more frequency gap carrier waves of calculating in one or more frequency channels of described communication system;
Use described FFT to export and calculate the performance number that is associated with described one or more frequency gap carrier waves; And
Use the performance number of being calculated to determine the existence of the adjacent-channel interference (ACI) in described one or more frequency channels of described communication system.
2. method according to claim 1, wherein, described calculating FFT output comprises:
The FFT output of the one or more high frequency side gap carrier waves of calculating in the high side of described one or more frequency channels; And
The FFT output of the one or more lower frequency side gap carrier waves of calculating in the downside of described one or more frequency channels.
3. method according to claim 2 further comprises:
The FFT output of the one or more central data subcarriers of calculating in the central frequency part of described one or more frequency channels; And
Calculate the performance number that is associated with described central data subcarrier, wherein, the existence of described definite ACI comprises the performance number of the described central data subcarrier that use is calculated.
4. method according to claim 3 further comprises:
Calculate first ratio between the described performance number of the described performance number of described one or more high frequency side gap carrier waves and described one or more central data subcarriers;
Calculate second ratio between the described performance number of the described performance number of described one or more lower frequency side gap carrier waves and described one or more central data subcarriers; And
Wherein, describedly determine to comprise: with described first ratio and described second ratio and threshold, to determine existing of ACI.
5. method according to claim 4 further comprises:
Based on calculating described threshold value about the 3rd ratio between the performance number of the performance number of one or more lower frequency side gap carrier waves of the described communication system that in the adjacent channel of communication system, do not have ACI and one or more central data subcarriers.
6. method according to claim 5 further comprises:
Adjust described threshold value according to one of false alarm rate and loss.
7. method according to claim 1 further comprises:
In OFDM (OFDMA) system, receive described one or more frequency channels.
8. method according to claim 1 further comprises: when determining the existing of described ACI, start and alleviate to alleviate described ACI.
9. wireless receiver comprises:
The fast Fourier transform (FFT) calculator is used for calculating in the fast Fourier transform (FFT) output adjacent to one or more frequency gap carrier waves of the first frequency channel of the second frequency channel of another system;
Be coupled at least one calculator of described FFT calculator, described at least one calculator is configured to use described FFT to export and calculates the performance number that is associated with described frequency gap carrier wave; And
Be coupled to the evaluator of described FFT calculator, described evaluator is configured to use the performance number of being calculated to determine the existence of the adjacent-channel interference (ACI) in described first frequency channel.
10. receiver according to claim 9, wherein, described one or more frequency gap carrier waves comprise:
One or more high frequency side gap carrier waves in the high side of described first frequency channel; And
One or more lower frequency side gap carrier waves in the downside of described first frequency channel.
11. receiver according to claim 10, wherein
Described fast Fourier transform (FFT) calculator further is configured to calculate the fast Fourier transform (FFT) output of the one or more central data subcarriers in the central frequency part of described first frequency channel;
Described at least one calculator is configured to calculate the performance number of described one or more central data subcarriers; And
Wherein, described evaluator is configured to use the described performance number of described central data subcarrier to determine the existence of the ACI in described first frequency channel.
12. receiver according to claim 11 further comprises:
The first ratio calculator, the described first ratio calculator are configured to calculate first ratio between the described performance number of the described performance number of described one or more high frequency side gap carrier waves and described one or more central data subcarriers;
The second ratio calculator, the described second ratio calculator are configured to calculate second ratio between the described performance number of the described performance number of described one or more lower frequency side gap carrier waves and described one or more central data subcarriers; And
Wherein, described evaluator further is configured to described first ratio and described second ratio and threshold, to determine the existing of ACI in described first frequency.
13. receiver according to claim 12 further comprises:
The threshold calculations device, described threshold calculations device is configured to: based on calculating described threshold value about the 3rd ratio between the performance number of the performance number of one or more lower frequency side gap carrier waves of the described communication system that do not have ACI in the adjacent channel of communication system and one or more central data subcarriers.
14. receiver according to claim 13 further comprises:
The threshold value adjuster, described threshold value adjuster operation is used for adjusting described threshold value according to one of false alarm rate and loss.
15. receiver according to claim 9 further comprises:
Receiving element, described receiving element are configured to receive described first frequency channel according to OFDM (OFDMA) agreement.
16. receiver according to claim 9 further comprises alleviating starter, the described starter that alleviates is configured to start alleviating of described ACI when determining the existing of described ACI.
17. a wireless receiver comprises:
Processor, described processor is configured to: calculate in the fast Fourier transform (FFT) output adjacent to the one or more frequency gap carrier waves in the first frequency channel of the second frequency channel of another system; Use described FFT to export and calculate the performance number that is associated with described frequency gap carrier wave; And use the performance number of being calculated to determine the existence of the adjacent-channel interference (ACI) in described first frequency channel; And
Memory, described memory are coupled to the result that described processor and operation are used for storage computation.
18. receiver according to claim 17, wherein, described one or more frequency gap carrier waves comprise:
One or more high frequency side gap carrier waves in the high side of described first frequency channel; And
One or more lower frequency side gap carrier waves in the downside of described first frequency channel.
19. receiver according to claim 18, wherein, described processor is further operated the fast Fourier transform (FFT) output that is used for calculating at central frequency one or more central data subcarriers partly of described first frequency channel; Calculate the performance number of described one or more central data subcarriers; And when the existing of described ACI of determining in described first frequency channel, also use the described performance number of described central data subcarrier to determine the existence of described ACI.
20. receiver according to claim 19, wherein, described processor further operation be used to calculate first ratio between the described performance number of the described performance number of described one or more high frequency side gap carrier waves and described one or more central data subcarriers; Calculate second ratio between the described performance number of the described performance number of described one or more lower frequency side gap carrier waves and described one or more central data subcarriers; And when determining the existing of described ACI, with described first ratio and described second ratio and threshold, to determine the described ACI in described first frequency.
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